In a long term evolution (LTE) in which services are to be provided, a multiple input multiple output (MIMO) system is used to improve the utilization efficiency of frequencies. A terminal used in the MIMO system is provided with a plurality of antennas, and can perform communications by simultaneously using a plurality of channels between the terminal and a base station. However, when the terminal is provided with a plurality of antennas, there occurs the problem that the coupling among the antennas degrades the transmission characteristic. For example, in the terminal provided with antennas A and B, the transmission characteristic can be degraded because a signal which is transmitted from the antenna A is absorbed by the other antenna B. To solve the problem, there is a device proposed to arrange a variable coupler between the antennas A and B, and perform control so that the amount of coupling of the variable coupler between the antennas A and B can increase during reception, and decrease during transmission.